Vulnerability Description
The io_uring subsystem in the Linux kernel allowed the MAX_RW_COUNT limit to be bypassed in the PROVIDE_BUFFERS operation, which led to negative values being usedin mem_rw when reading /proc/<PID>/mem. This could be used to create a heap overflow leading to arbitrary code execution in the kernel. It was addressed via commit d1f82808877b ("io_uring: truncate lengths larger than MAX_RW_COUNT on provide buffers") (v5.13-rc1) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. It was introduced in ddf0322db79c ("io_uring: add IORING_OP_PROVIDE_BUFFERS") (v5.7-rc1).
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Linux | Linux Kernel | >= 5.7, < 5.10.37 |
| Canonical | Ubuntu Linux | 20.04 |
Related Weaknesses (CWE)
References
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d1PatchVendor Advisory
- https://security.netapp.com/advisory/ntap-20210716-0004/Third Party Advisory
- https://ubuntu.com/security/notices/USN-4949-1Third Party Advisory
- https://ubuntu.com/security/notices/USN-4950-1Third Party Advisory
- https://www.openwall.com/lists/oss-security/2021/05/11/13Mailing ListPatchThird Party Advisory
- https://www.zerodayinitiative.com/advisories/ZDI-21-589/Third Party AdvisoryVDB Entry
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d1PatchVendor Advisory
- https://security.netapp.com/advisory/ntap-20210716-0004/Third Party Advisory
- https://ubuntu.com/security/notices/USN-4949-1Third Party Advisory
- https://ubuntu.com/security/notices/USN-4950-1Third Party Advisory
- https://www.openwall.com/lists/oss-security/2021/05/11/13Mailing ListPatchThird Party Advisory
- https://www.zerodayinitiative.com/advisories/ZDI-21-589/Third Party AdvisoryVDB Entry
FAQ
What is CVE-2021-3491?
CVE-2021-3491 is a vulnerability with a CVSS score of 7.8 (HIGH). The io_uring subsystem in the Linux kernel allowed the MAX_RW_COUNT limit to be bypassed in the PROVIDE_BUFFERS operation, which led to negative values being usedin mem_rw when reading /proc/<PID>/mem...
How severe is CVE-2021-3491?
CVE-2021-3491 has been rated HIGH with a CVSS base score of 7.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2021-3491?
Check the references section above for vendor advisories and patch information. Affected products include: Linux Linux Kernel, Canonical Ubuntu Linux.